N
Need-to-build
I have been told (Cal-Tech Engineer) that ducted fans are only practical at high speeds (over 300 mph) anything below that speed, propellers should be used. Then I have read that Ducted fans are more practical at lower speeds (below 200 mph)then propellers. Now....who or what is right? Also, are there any "good" books on that subject. I would ike to do some design work on a Ducted fan aircraft using a wankel or other high rpm engines.